If you get such a garbage when launching Firefox (official deb package, not the crappy snap one) from the command line or as an external browser for Newsboat, try force disabling accessibility as suggested here.
» firefox
~
» [Parent 25471, Main Thread] WARNING: invalid (NULL) pointer instance: 'glib warning', file /build/firefox-LOPdVD/firefox-119.0+build2/toolkit/xre/nsSigHandlers.cpp:167
(firefox:25471): GLib-GObject-WARNING **: 11:46:47.027: invalid (NULL) pointer instance
[Parent 25471, Main Thread] WARNING: g_signal_emit_by_name: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed: 'glib warning', file /build/firefox-LOPdVD/firefox-119.0+build2/toolkit/xre/nsSigHandlers.cpp:167
(firefox:25471): GLib-GObject-CRITICAL **: 11:46:47.027: g_signal_emit_by_name: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed
[Parent 25471, Main Thread] WARNING: invalid (NULL) pointer instance: 'glib warning', file /build/firefox-LOPdVD/firefox-119.0+build2/toolkit/xre/nsSigHandlers.cpp:167
(firefox:25471): GLib-GObject-WARNING **: 11:46:47.027: invalid (NULL) pointer instance
[Parent 25471, Main Thread] WARNING: g_signal_emit_by_name: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed: 'glib warning', file /build/firefox-LOPdVD/firefox-119.0+build2/toolkit/xre/nsSigHandlers.cpp:167
(firefox:25471): GLib-GObject-CRITICAL **: 11:46:47.027: g_signal_emit_by_name: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed